Answer:
[tex]B.\ \ a_n=(-9)+(n-1)6[/tex]
Step-by-step explanation:
[tex]a_1=-9\,,\ a_2=-3\,,\ a_3=3\,,\ a_4=9\,,\ a_5=15...\implies d=6[/tex]
{-9-(-3)=6 and 3-(-3)=6 and 9-3=6 and 15-9=6}
An arithmetic sequence is: [tex]a_n=a_1+(n-1)d[/tex]
[tex]a_1=-9\quad and\quad d=6[/tex]
[tex]a_n=-9+(n-1)\cdot6[/tex]
